Hi!
My understanding is that we want to clear local_specializations even when
saved_local_specializations is NULL, if the current function created
the local_specializations htab (otherwise it isn't local, but global).
The problem with that is that it isn't GTY marked and contains TREE_LIST
nodes not references from elsewhere, so the next time we look at the
hashtable we can ICE if they have been GC collected and reused for something
else.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
In the PR there is also a patch to switch local_specializations into
a pointer_map, I think that would be more efficient, but probably 4.8
material, right?
2012-01-27 Jakub Jelinek <ja...@redhat.com>
PR c++/51852
* pt.c (tsubst_pack_expansion): Delete and restore
local_specialization whenever need_local_specialization, not just
when saved_local_specializations is non-NULL.
* g++.dg/other/gc5.C: New test.
--- gcc/cp/pt.c.jj 2012-01-26 09:22:19.000000000 +0100
+++ gcc/cp/pt.c 2012-01-27 10:10:38.566458106 +0100
@@ -9582,7 +9582,7 @@ tsubst_pack_expansion (tree t, tree args
}
}
- if (saved_local_specializations)
+ if (need_local_specializations)
{
htab_delete (local_specializations);
local_specializations = saved_local_specializations;
--- gcc/testsuite/g++.dg/other/gc5.C.jj 2012-01-27 11:34:51.722005604 +0100
+++ gcc/testsuite/g++.dg/other/gc5.C 2012-01-27 11:33:24.000000000 +0100
@@ -0,0 +1,27 @@
+// PR c++/51852
+// { dg-do compile }
+// { dg-options "-std=gnu++11 --param ggc-min-heapsize=0 --param
ggc-min-expand=0" }
+
+template <typename, typename>
+class transformed {};
+
+template <class R, class F>
+transformed<F, R> transform (R r, F f);
+
+template <typename, typename>
+class joined {};
+
+template <typename T, typename U>
+joined<T, U> join (T t, U u);
+
+template <typename T, typename U, typename V, typename... Rest>
+auto join (T t, U u, V v, Rest... rest) -> decltype (join (join (t, u), v,
rest...));
+
+template <typename F, typename... Rs>
+auto polymorphic_transform (F f, Rs... rs) -> decltype (join (transform(rs,
f)...));
+
+int
+main ()
+{
+ polymorphic_transform (0, 0, 0);
+}
Jakub
